If you're 80+ and can solo Molten Core trash, consider doing it while doing BG, dungeon, or anything. The item that is of interest is called Blood of the Mountain. They drop off only 1 mob: Molten Destroyer. On my server (both faction) they sell for around 1,000g each.
Map of the mob's spawn location:
Go there and kill every Molten Destroyer you see and loot the Blood of the Mountain, and maybe occasional BOE purple. I usually find one per run. When you're done, just que and have fun while you wait for soft reset (30 minutes minimum). After soft reset, the trash fully respawns including Destroyers. I have done this for a while and can confirm that Blood of the Mountain can continue to drop every time. Even after you've killed the bosses (all including Rags)
I do this fairly often in between BGs and it only takes me at most 10 minutes. Most of the trash mobs ignores me as 85 player unless I stomp on their toes.
Why Blood of the Mountain? You need 10 of it to make an epic item Sulfuron Hammer and people wants to get this for achievement but don't want to take a few hours or weeks to farm the item. Other items (Lava core, Fiery core, etc) needed for the hammer also drops there but I rarely bother looting them because on my server the AH is flooded with them as they are common drop and not worth fighting with other sellers for a few gold.